Light absorber for cameras



Jan. 1, 1924 w. SPARKS LIGHT ABSORBER FOR CAMERAS Filed April 18, 1922Patented Jan. 1, 1924.

IFQRNEA, TO THE LIGHT-ABSORBER AJJCISGO, GALIFORNIA, A 'TJORPOEATION SFCALI- LIGHT ABSQRBER F03 CAMERAS.

Application. flied April 18, 1922. Serial Ho. 555,353.

51% (ZZZ whom may oonceem:

He. it known thin:- I, WILL SPARKS, a cit izen oi the United States, anda resident of the city and couniy of San l i'unciseo, State ofCalifornia, have made a new and useful invention, to it, Improvements inLight Absorbers for Panic-ins; and l deciare the ioiiowingi to he: :ifuii, oise, and emu-i: ileseriniion o i i 'fiiheinvention rein I I moansfor arresting. impounding and an orbin r indirect iigrhi rays incameras- \vi'ih the object preventing time "(Ciiiilfl or fog grii'ig oithe photographic pinto by iE'HiiIfiCil rays of ii zhi. z'oi'ioeteii o(YUP-L oi'idf'iii'i Wiiilin the Uiher and zu ivair ages will appear thisdescription progrosses.

-' i 1 In ihis specification and the annexeq drawings, the lifl'filliimlis iiiusiiraiieii in the form vonsidereii to he the best but it is io ieunderstood,ihrii' the iIWQHilOH '1: not him Z :i in oiiier forum. and iii stood thin in am! in ihe ehziins 'foiiowing' the description it isdesired in cover the in'i'ention in whatsoever form it may he embodied.

photograph the .fll21IO oi the object projecieii on a phoiogrnyhiv phitein proper proportion is; sharper in definition zinii shows greater depthin :nrzi iniineiiiui'eiy UIiOHDfiiUQ the axis of {he iensr whioh is hefocal point on tho phoioginphiu phite. )wing in the inevhnni 1 wow i'm'iion of i'he rhese desirzxhie quuiiiies .iiiiliiliFil as ihe ,ier marginM iii! pizne is IlZiHiiWi. due to mei'hnniirui z'iiui iipiii'fii iiffii'zliiflllfi created h s iie ions. The gi'euh-r the (wavering powerof Tho h-ns. ii hii'oer the Pen surrounding i he. 305 11 :1 II\ \vii'hinwin the image is IZIOS'i true. hrreiore. ions niih 'i'ent ooi" TWiii! ofangle is i" ild.i]ii,

wring: power or x for (ovormg SQX'LWLXYQ pin les even of eniai motionpirinre iiifii or the ii A 15 of tine hiige vim-ring power hzis li'F?pim'er all the iizne. zimi ii" :1 iiilfji pixie in presented in it. themargins oi its iiehi nil upon and light "(he inside oi the minein. fiomeof bhis indirect iigin. s; niiei. r the plane tends o veii she.negiiiii'e making: it neoesszzrjv 5 0 stop iiO'WD the which destroysmuch its speed iiinanimation In the :ioooinpnnying one sheet of drawi15. i A minnniatic ieplesentation o (I. nho'bo' ru'ohuearners in crosssection. hav- E". r h inn: iliUS HTVQIIUOD applied EiiQZQiIO.

fig. 2 is an end eie lil1 of the nested soptzims detached o 111g, 3 IS aside seotion.

F i is a perspective View of a modification of the septum.

In ii the comirue'zion illustrated in from the lens mounting. View ofthe same, in cross inciu theiens i of any (:oni'eniiom construction, insuitzihie mounting eiidzihi adjustable within the housing 3 ix'ed to thefront hoard 4 of the camera box in any suitaioiev manner. The tubularism mounting Q adjusted within 3 by the pinion 5 engaging rack teethffi'"1i'i@fi in the housing 2 the pinion heing nteii by the im urieii'handle 6, in the nsnzii innnnen The camera consists of the conventionallight tight ha 7. having :1 phue hohier 3 slidabie therein andcontaining :1 nonsiiive plate 9 in proper focal relation to the iene i.which is provided with the usual siop 10 proportioneri it the focaldistance hetn'een the ion? and the piiii'e. all of which eons znoiion isconventional and diagrziininsitir ziiy iiinetrateii and is not to heconsfi'ued {HR iimiting this invention. which aimiio ijh: every form ofphotography lens or iiinminnting aperture aphio Hensiiive surface such.imi

in heavy black dotted lines A and B. croesin at the axis of the lensrepresent. the in "en-ii hreuciih of the cone of light rays oom eyi (hein'iapje of the object to II he photogn plied to the full area of theplate the lens 1 to iii 9 exposed therein. Presumingby light dottedlines crossing at the axis of the lens, will enter and illuminate theinterior of the camera without falling directly upon the exposed plate.Inasmuch as only the direct rays of light can convey a true image to theplate, these lateral or excess rays striking the interior surfaces ofthe camera or the lens mounting will be reflected therefrom, each at anangle equal to its angle of incidence which will project them across themain rays A and B onto the lateral margins of the sensitive plate 9.whereon they will impress their indirect images causing a confusion ofimages, resulting in what is variously described as flare, fog andveiling. It is on account of this scatter of light from even theblackest camera interior. that a lens, the field of which falls sharplyoft altogether, such as a portrait lens and some anastigmats, effort ismade to minimize the fogging by using a camera several times larger thannecessary for the plate area exposed, the Whole image then falling atthe end of the camera facing the lens without serious reflection oflight, This is obviously an impractical expedient not fully effective atbest.

The means I prefer in accomplishing the objects of this invention andobviating the disadvantages set forth, include a series of septunis,such as l2, l3, 14 and 15, interspaced and arranged concentricallywithin the lens mounting and directed substantially parallel withtherays 01 light passing through the lens, in accordance with theirdistance "from the lens. The last septum. 15 being arranged in proximityto the cone formed by the angle A and B, the true image passesunobstructed from the lens to the base of the cone illuminatin the plate9. These septums are of suitable opaque material, preferably painteddull black or coated with any suitable light absorbing substance. Thelight rays projected at angles lateral to the cone A-B are directed intothe spaces or cells between these septums, wherein they are impounded orabsorbed or prevented from reflecting on lines suchas indicated by thedot and dash lines, which would causethe flare or fogging of the plateif the septums were not present to intersect them. In a relatively shortfocus lens, one septum may be sufficient. However, in a long focus lensconditions such as indicated in Fig. 1 are improved by a multiplicity orduplication of the septums as shown, by whichmeans all wide anglerays,-such as C-C are intercepted and killed and a node of darknesscreatedaround the direct cone of light. The operation of this inventionis not to be confused with more light absorbing surfaces or dulledfinish, but comprehends a cellular structure capable of impounding thelight can take the shape of the lens mounting or intcrior of" thecamera, whether it be square, p -'ramidal, or any regular or irregularshape, requiring a consistent modification of the septums, as in Fig. 4where the septums are designated by the characters 12, 13, 14 and 15.

Having thus described this invention, what I claim and desire tosecure-by Letters Patcut is:

1. In a photographic camera means intermediate the lens and the platethereof and tapering toward the axis of the lens for preventing all butdirect light rays reaching said plate.

2. In a photographic camera having an aperture and a plate cellularmeans within said camera coaxially with and tapering to ward saidaperture adapted to absorb all light rays not directly projected uponsaid plate through said aperture.

3. In a photographic camera having a plate and an aperture adapted todirect a cone of light onto said plate; opaque septums interposedbetween the light rays within said camera outside-of said cone of lightcoaxially with and tapering toward said aperture.

4. In combination with a lens and mlluntmg; a septum in said mountingarranged coaxially with and tapering toward said lens, the angle oftaper of said septum approximating the angle of projection of the lightray projected toward it by said lens.

5.- In combination with a lens and mounting; inter-spaced septums insaid mounting, directed toward the center and spaced back from saidlens.

6. In combination. with a lens and mounting; intcrspaced tubular septumsarranged in said mounting coaxially with and tapering toward said lens,the angle of taper of each septum approximating the angle of pro jectionof the light ray projected toward it by said lens.

In testimony whereof, I have hereunto set my hand at San Francisco,California, this 27th day of January, 1922.

WILL SPARKS.

In presence of-- LINCOLN V. JoHNsoN.

